FIG. 1.

Growth curves showing the activities of selected antibiotics and drugs (4 μg/ml) against NB. Each drug treatment was plotted against the positive (drug-free) growth control (•). (A) ▪, negative control (growth medium only); ▵, tetracycline; ▿, nitrofurantoin; ◃, etidronate. Note that the lines for the calcium inhibitor etidronate, tetracycline, and nitrofurantoin are almost identical to that for the negative control. (B) ▾, ampicillin; ○, doxycycline; ⧫, 5-FU. Note the marked difference in inhibition between tetracycline (A) and doxycycline (B). While some initial minimal growth was exhibited by NB exposed to ampicillin on day 4, there was no significant growth for the duration of the test period. The curve for 5-FU mimics that for the negative control in panel A. (C) □, gentamicin; ⧫, vancomycin. NB exposed to both gentamicin and vancomycin exhibited a 1- to 2-generation delay in growth compared to the growth control and then resumed growth in a pattern similar to that for the positive growth control. mAbs, milli-absorbance (10⁻³ A₆₅₀).